This invention relates to the field of blowers. In particular, this invention is drawn to blower impeller designs.
Cabinetry or enclosures for heat generating equipment may contain one or more blowers for active or forced air cooling. The blower displaces the air within the enclosure volume with cooler air external to the enclosure volume. The blower acts as a pump to transfer air between the two environments. Depending upon the configuration, either the air within the enclosure or the air external to the enclosure is the source for the pump. Air pumped from the interior by the blower is replaced with air external to the enclosure through the vents. Alternatively, air pumped from the exterior of the enclosure into the enclosure displaces the air in the enclosure through the vents. Without active cooling, the components within the cabinetry can overheat resulting in erratic, unpredictable behavior or a shortened lifespan among other maladies.
Blower systems may incorporate multiple blowers for redundancy or to achieve a specific air flow pattern in order to ensure adequate cooling. The failure of a single blower, however, creates a new source for air. Moreover, the blower interface between the internal/external environments tends to be more efficient for transferring air than the enclosure vents. The blower interface thus tends to become a preferential source relative to the vents for the transfer of air. As a result, the air flow patterns within the enclosure may be sufficiently disrupted to prevent adequate cooling or to significantly decrease the efficiency of redundant blower systems.
One approach uses baffles to prevent reverse airflow. These baffles have a number of members that pivot to enable opening and closing the baffle. When the blower is off, gravity or other forces close the baffle. During normal operation, simple baffles rely upon the pressure developed by the blower to open. One disadvantage of simple baffles for equipment enclosures is the additional assembly steps required to mount the baffles on the equipment. Another disadvantage of simple baffles is that the baffles members significantly impeded the flow of air from the blower exhaust.
In view of limitations of known systems and methods, blower designs for vented enclosures are described. One blower design incorporates an impeller having a plurality of blades. A plurality of one way valves are interleaved between the blades to permit substantial airflow only in one direction.
In one embodiment, each blade is coupled to one of an impeller body or a corresponding blade with a spring loaded hinge. When the impeller has a rotational speed below a threshold range the flaps remain in a closed position substantially restricting air flow between the blades. The flaps open to permit air flow between the blades when the rotational speed exceeds the threshold range.
In an alternative embodiment, the impeller comprises a plurality of blades and a plurality of flexible flaps interleaved between the blades. Each flap is coupled to one of an impeller body or a corresponding blade. When the impeller has a rotational speed below a threshold range the flaps remain in a closed position substantially restricting air flow between the blades. The flaps flex open to permit air flow between the blades when the rotational speed exceeds the threshold range.
In another embodiment, an impeller includes a plurality of blades and a hub insert having a plurality of valves. The hub is disposed within an inner periphery of the impeller such that the valves and blades are interleaved. The valves remain in a closed position substantially restricting air flow between the blades when the impeller has a rotational speed below a threshold range. The valves open to permit air flow between the blades when the impeller speed exceeds the threshold range. In one embodiment, the hub further comprises a flexible strip with a plurality of flaps. A separation distance between the flaps is substantially equivalent to the distance between the leading edges of the blades.
In various embodiments, the impeller is configured for centrifugal pumping action. In various embodiments, the impeller blades form one of an airfoil, backward inclined, backward curved, radial, paddle and forward curved configuration.
Other features and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description that follows below.